The application of dyes to fibrous objects has taken place since before recorded history. Application of natural dyes to textiles has been industrially important since at least the twelfth century. Much more recently, the discovery of numerous synthetic dyes has expanded the use of dyeing process but the extensive use of synthetic fibers has resulted in a considerable number of complications when dyes are to be applied to such synthetic materials for textile and other applications.
Dyeing describes the impregnation of objects such as paper, textiles and leather with a new color which is usually permanent. The process of dyeing includes dissolution or dispersion of the dye in a liquid medium and subsequent application to the object whose dyeing is desired to attach the dye to the object by chemical or physical means. Water is often preferred as the liquid medium although non-aqueous media have been employed.
The success of the dyeing process is at least in part a function of the chemical nature of the dye as well as the chemical nature of the object to be dyed. Fibers of materials such as cotton, wool and Nylon incorporate functional groups which are hydrophilic in character and give good results when ionic dyes, e.g., acid dyes, are applied. Fibers of other materials such as Rayon (cellulose acetate) or polyester (polyethylene terephthalate) are hydrophobic in character and do not respond well to ionic dyes. Better results are obtained in the dyeing of polyester or other hydrophobic fibers if the dye is of the class of dyes termed disperse dyes. Such dyes are only slightly soluble in water but under the conditions of dyeing are sufficiently soluble to penetrate the fibers to some extent. The dyeing of the fibers of nonionic hydrophobic material is improved, however, through the use of a carrier. The carriers, which are well known and understood in the art, are frequently aromatic in character and have solubility characteristics similar to the fiber to be dyed and many of the disperse dyes. The carrier is thought to loosen interpolymer bonds of the fiber and promote dispersion of the dye into the hydrophobic polymer. However, the use of a carrier creates other difficulties in that the carrier is only slightly soluble in aqueous medium and emulsifiers must be used to disperse the carrier in the dyebath.
The use of a carrier during the dyeing of polyester or other hydrophobic polymers is avoided on occasion if vigorous dyeing conditions are employed. Such conditions typically include a temperature at least substantially above 100.degree. C. and superatmospheric pressures to permit the use of these temperatures with an aqueous medium. It is at least in part because of these considerations that the dyeing of fibers of nonionic, hydrophobic polymers is relatively difficult and/or expensive to effect. For an extensive discussion of dyes, and the dyeing process see Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, Volume 8, John Wiley & Sons, 1979, pages 151-158, 280-297, 304-308 and 323-324. Some physical procedures have been used to facilitate polyester fiber dyeing. Frankfort, U.S. Pat. No. 4,134,882, discloses better dyeing with fibers spun with extremely high withdrawal speeds. Hasler et al; U.S. Pat. No. 4,432,770, obtain better results with combination of two or more dyes.
An additional class of polymers which are nonionic and hydrophobic is the broad class of polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon. Early examples of such polymers are the carbon monoxide/ethylene copolymers described by Michel et al; U.S. Pat. No. 3,068,201, which are produced by free-radical polymerization. These polymers, which are random and of variable proportions of carbon monoxide and ethylene units, are said to have low dye-receptivity. The object of Michel et al. is to chemically modify the carbon monoxide/ethylene copolymers to improve certain properties of the polymer including dye receptivity.
More recently the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon has become well known in the art. Such polymers, also termed polyketones or polyketone polymers, are represented by the repeating formula ##STR1## wherein A independently is a moiety of at least one ethylenically unsaturated hydrocarbon polymerized through the ethylenic unsaturation thereof. Such polyketone polymers would be expected to receive dye only with difficulty because of the nonionic and hydrophobic character of the polymers. Lutz, U.S. Pat. No. 4,824,910 describes blends of such polyketone polymer with minor proportions of poly(vinylpyridine). Lutz states that incorporation of the vinylpyridine polymer into the polyketone matrix should in effect increase the dye-reactivity of the polyketone polymer. The information of the blend serves to provide a material which will have more hydrophillic character and thus increased dye-receptivity.
It would be of advantage to have a process for the dyeing of fibers of linear alternating polymer of carbon monoxide and at least one ethylenically unsaturated hydrocarbon without the need for the provision of a carrier or the use of vigorous dyeing conditions, but which provides dyed polyketone polymer fibers of good properties.